BAll joints are not seperate from Renault they are complete ball joints there are people who will tell you that you can use scenic ball joints but the sake of £20 complete wishbone FTW.
My local car factors lists two ball joints for Clios including Sports, one has 10mm studs, the other 12mm studs, he had both in stock so I took the 12mm studs (as even if too big I'd drill out to suit) but they are correct for my car, cost £7 each, bit of a saving over the £50 odd Renault want for wishbones.
Then I'd take my saving and buy the Powerflex wishbone bushes fit them myself and still save money and have a tighter front end on my car.